Addition Of CeO2 Research Articles

Graphene oxide–cerium oxide hybrids for enhancement of mechanical properties and corrosion resistance of epoxy coatings

In this study, graphene oxide–cerium oxide (GO–CeO2) hybrids were synthesized through an in situ hydrothermal approach and were incorporated into epoxy resin to prepare a robust coating for aluminum alloy protection. The mechanical properties of the GO–CeO2-loaded coating were characterized by nano-indentation, friction-wear test and pull-off adhesion test, using pristine epoxy coating and GO-loaded epoxy coating for comparison. Results revealed that GO–CeO2 addition could increase the hardness, elastic modulus and the wear resistance and decrease the friction coefficient of the composite coating. Compared with pristine epoxy coating, the adhesion strength of GO–CeO2/epoxy coating increased from 7.3 MPa to 12.2 MPa. Such improvement in the mechanical properties can be explained by the good dispersion of GO–CeO2 in the composite coating. In addition, salt spray and electrochemical impedance spectroscopy (EIS) measurement results showed that the corrosion resistance of the GO–CeO2-loaded coating was significantly enhanced. After 30 days of salt spray test, the coating resistance of the GO–CeO2/epoxy coating was 17.8 and 3.5 times higher compared with that of the blank epoxy coating and GO/epoxy coating, respectively. The superior barrier performance of the composite coating was mainly ascribed to the synergistic effects of the prolonged pathway against corrosive media permeation and the corrosion inhibition effect of CeO2 particles.

Synthesis of C21H38ClN Assisted Si Pillared Clays and the Effects of CeO2 Addition on Its Supported Palladium Catalyst for Benzene Oxidation

Mesoporous silica-pillared clays (SPC) were prepared with C21H38ClN cationic surfactant as template and supported PdOx catalysts were prepared by impregnation method. The influence of addition of CeO2 on benzene combustion was evaluated. The samples were characterized by N2 adsorption–desorption, XRD, XPS, HRTEM and TPSR. Compared with the raw montmorillonite, the d001 value of SPC increased from 0.96 to 3.45 nm. Furthermore, the surface area was increased from 30 to 835 m2/g and the pore volume was increased from 0.11 to 1.30 cm3/g, respectively. The addition of CeO2 increased oxygen vacancies and improved the dispersion of PdOx on SPC, and the optimal addition of CeO2 was 10%. Therefore, of all the catalysts, 0.3%Pd/10%Ce/SPC could completely oxidize benzene at 280 °C, showing the highest catalytic activity. This catalyst showed high activity for benzene oxidation in wet conditions with or without Cl− displaying good durability, which should be related to the presence of Ce3+ on the surface of catalyst after reaction. The excellent pore structure of SPC, improved dispersion of PdOx and high concentration of Ce3+ on the catalyst surface were the key factors for the high catalytic activity of 0.3%Pd/10%Ce/SPC. Mesoporous silica-pillared clays (SPC) were synthesized and SPC supported CeO2 and PdO catalysts were prepared by impregnation method. The 0.3% Pd/10% Ce/SPC catalyst displayed the highest activity for benzene combustion.

Improved Water-Gas Shift Performance of Au/NiAl LDHs Nanostructured Catalysts via CeO2 Addition.

Supported gold on co-precipitated nanosized NiAl layered double hydroxides (LDHs) was studied as an effective catalyst for medium-temperature water–gas shift (WGS) reaction, an industrial catalytic process traditionally applied for the reduction in the amount of CO in the synthesis gas and production of pure hydrogen. The motivation of the present study was to improve the performance of the Au/NiAl catalyst via modification by CeO2. An innovative approach for the direct deposition of ceria (1, 3 or 5 wt.%) on NiAl-LDH, based on the precipitation of Ce3+ ions with 1M NaOH, was developed. The proposed method allows us to obtain the CeO2 phase and to preserve the NiAl layered structure by avoiding the calcination treatment. The synthesis of Au-containing samples was performed through the deposition–precipitation method. The as-prepared and WGS-tested samples were characterized by X-ray powder diffraction, N2-physisorption and X-ray photoelectron spectroscopy in order to clarify the effects of Au and CeO2 loading on the structure, phase composition, textural and electronic properties and activity of the catalysts. The reduction behavior of the studied samples was evaluated by temperature-programmed reduction. The WGS performance of Au/NiAl catalysts was significantly affected by the addition of CeO2. A favorable role of ceria was revealed by comparison of CO conversion degree at 220 °C reached by 3 wt.% CeO2-modified and ceria-free Au/NiAl samples (98.8 and 83.4%, respectively). It can be stated that tuning the properties of Au/NiAl LDH via CeO2 addition offers catalysts with possibilities for practical application owing to innovative synthesis and improved WGS performance.

Mixed Films Based on MgO for Secondary Electron Emission Application: General Trends and MOCVD Prospects

Doping process is widely used to improving emission performance of MgO films thicker than 10 nm via assisting the surface recharge and changing in electron structure. The present paper briefly reviews this strategy in a search for the new materials and structures being effective for secondary electron emission (SEE) and their diagnostics. Then, Metal-Organic Chemical Vapor Deposition (MOCVD) coupled with the specially selected precursor is suggested here as a new technique that transforms the refractory oxides to nanoscale, defect-disordered materials able to solid-solid interaction at 450 °C. Primary experiments have been performed for demanded mixed films based on MgO with ZrO2 and CeO2 additions. A dopant impact on facilitating the formation of oxygen vacancies in the host oxide and on the features of new mixed phases have been studied by new diagnostic means, based primarily on chemical method of differential dissolution. The method brought out the effective solvents that were the probes for identifying the nanoscale and amorphous phases possessing by the different defects on the surface of MgO films and determining contents of these phases. This approach allowed us to explain the origin of mixed phases and to estimate contribution of each from them in the macroscopic SEE properties.

Effect of the Addition of CeO2 on the Microstructure and Corrosion of in-situ TiB/Ti Composite Coatings Prepared by Laser Cladding Technology

Effect of the Addition of CeO2 on the Microstructure and Corrosion of in-situ TiB/Ti Composite Coatings Prepared by Laser Cladding Technology

Effects of Diesel Fuel Nano-Additives on Friction and Wear Properties of Precision Coupled Parts of a Diesel Engine Fuel Injection System

Due to the unique redox characteristic of CeO2, the addition of CeO2 in diesel fuel reduces diesel engine emissions; however, its influence on the friction and wear performance of fuel injection systems is not clear. In this work, CeO2 was synthesized and modified. CeO2–diesel fuel blends with different concentrations were prepared. The dispersion stability of the CeO2 and modified CeO2 in diesel fuel blends was measured. The results indicated that the dispersion stability of the modified CeO2 in diesel fuel was improved. The effects of adding modified CeO2 to diesel fuel on the friction and wear properties of the fuel injector body were studied. Test results showed that the friction coefficients of all of the diesel fuel blends were the same after running in at normal temperature. At high temperature, the friction coefficients of diesel fuel blends with 10, 25, 50, and 100 ppm CeO2 added were reduced by 14.03, 25.27, 24.31, and 10.58%, respectively, compared with that of neat diesel fuel. Both the width and maximum depth of the wear scar were reduced to different degrees, and the diesel fuel blend dosed with 25 ppm CeO2 had the best antiwear ability at normal temperature and high temperature.HIGHLIGHTSThe morphology of modified CeO2 was spherical and relatively uniform.The dispersion stability of modified CeO2 in diesel fuel was improved.The addition of CeO2 in diesel fuel improved the friction and wear performance.With an increase in CeO2, the range of improvement first increased and then decreased.The diesel fuel blend with 25 ppm CeO2 added showed the best friction and wear performance.

Effect of CeO2 on microstructures and mechanical properties of welded high-strength steel weld metal

The effect of CeO2 on the microstructures and mechanical properties of welded high-strength steel weld metal was investigated by optical microscopy, scanning electron microscopy and mechanical testing. The results demonstrate that the addition of CeO2 can promote the refinement and spheroidization of inclusions, refine the grains, and form acicular ferrites in the weld metals. When the addition of CeO2 increased from 0% to 3%, the content of bainites gradually decreased, and the lath structure disappeared. The formation of the acicular ferrite ductile phase inhibited the formation of bainites and other strengthened phases in the weld metals, and the microstructure of acicular ferrites was excessive. When the CeO2 content was 1%, the tensile strength was 903 MPa, the yield strength was 848 MPa, and the low-temperature impact toughness was 61 J at −40 °C. When the CeO2 content was 3%, the low-temperature impact toughness of the weld metal gradually increased to a maximum value of 71 J. The weld metal had the highest toughness but the lowest strength. The addition of CeO2 changed the pattern of crack generation, and the fracture mode changed from quasi-cleavage fractures to ductile fractures with dimples. To achieve a good matching of strength and toughness, the wire No. 2 with 1% CeO2 had the best comprehensive mechanical properties.

Structural Role of CeO<sub>2</sub> in the Modified Borate Glass-Ceramics

A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and 31P NMR spectroscopy. The microstructures of samples contain 2 are amorphous in nature. More addition of CeO2 transforms the glass to glass-ceramics without thermal annealing. The morphological change of the microstructure of these materials was followed by transmission electron microscopy (TEM). The obtained results have revealed that the addition of more than 0.8 mol% CeO2 can promote nucleation and crystallization routes that are combined with the establishment of diverse crystalline phases. Glasses with lower contents of CeO2showed no tendency to crystallization. The crystals of CeO2 containing glasses were spheroid like morphology that was assigned to the three-dimensional fast growth of the well-formed structural species in the boro-apatite phase. In addition, the cerium free glass is characterized by particle-like morphology. Then the growth of spheroid species in three-dimension plays better compatibility and bioactivity behavior than that of the other types of morphology. This is may because the spherical shape has a higher surface area than that of the needle-like morphology. Accumulation and aggregation of small-sized spheres from cerium borate phases played the role of enhancing the hardness of the studied materials.

Ni and Cu oxide supported γ-Al2O3 packed DBD plasma reactor for CO2 activation

The direct activation of undiluted CO2 is carried out in a co-axial dielectric barrier discharge (DBD) reactor. The variation of the electrical discharge parameters and their influence on CO2 decomposition is investigated with the integration of 15 % MO/γ-Al2O3 (M = Ni, Cu) catalyst in the discharge zone. The electrical discharge is found to shift from the filamentary to a combination of surface and micro filamentary discharge on catalyst integration to NTP and also leads to the higher conversion of CO2 than DBD alone. The highest conversion of CO2 (15.7 %) with the energy efficiency of 1.597 mmol/kJ is achieved under CuO/γ-Al2O3 integrated NTP system, whereas the maximum of carbon balance (94.4 %) reaches with 4% CeO2 addition to CuO/Al2O3 catalyst. The oxygen vacancy of the catalyst plays a vital role in improving the performance, especially, the oxygen buffer property of CeO2 facilitates the recombination reaction and contributes to obtaining the highest carbon balance.

Fabrication and experimental analysis of hydroxyapatite based composite materials for medical implants

Abstract Hydroxyapatite is the main inorganic component of bones and teeth. It has been extensively used as an implant material for bone substitute owing to its excellent biocompatible properties. Hydroxyapatite based composite materials shows significant properties in the field of biomedical applications. In our present work, Hydroxyapatite was synthesized via wet chemical precipitation reaction. Then four types of Hydroxyapatite based composites with 7.5 wt% each of Zinc oxide (ZnO), Titanium dioxide (TiO2), Ferric oxide (Fe2O3) and Ceria (Ce2O) via conventional sintering. The density of these composite materials was measured experimentally by Archimedes principle and compared with the theoretical density. The porosity of each composite material is calculated. X-ray diffraction (XRD) analysis was carried out to identify different phase. Scanning Electron Microscope (SEM) analysis confirms the porosity. Energy dispersive spectroscopy was used to determine the ratio of different elements. The hardness of the composite materials was evaluated using Vickers’ hardness tester. The compressive strength was evaluated using Compression test. It was observed that hardness and compressive strength of composite material increased with the addition of Fe2O3, ZnO, CeO2 and TiO2. However, the maximum value of hardness and compressive strength increased with the addition of Fe2O3 and were found to be 7.4 GPa and 406.3 MPa respectively. SEM micrographs clearly exhibit least porosity in HAP-Fe2O3 samples which contributes to enhancement of mechanical properties.

Bifunctional Ni-Ca based material for integrated CO2 capture and conversion via calcium-looping dry reforming

Effective integration of CO2 capture and its conversion is an attractive strategy to reduce the anthropogenic CO2 emissions meanwhile achieve the potential revenue of CO2 molecule. Calcium-looping dry reforming of methane (CaLDRM) has emerged as such a promising process, implemented over a bifunctional reactor combining a CaO-based sorbent and a Ni-based catalyst, to achieve CO2 capture and in-situ conversion with CH4 into syngas. Herein, we synthesize a bifunctional Ni-Ca based material, i.e. Ni and CeO2 nanoparticles co-loaded on ZrO2-coated CaCO3, which enables isothermal capture and release of CO2 at the temperature favorable for DRM reaction, allowing to operate CaLDRM process in a single reactor by simple gas switching. Thanks to the stabilization effect of the ZrO2 layer, both CaO and Ni particles are exempted from severe sintering, maintaining the activity of capture and catalysis. The addition of CeO2 contributes not only to combat the accumulation of inactive carbon during long-term DRM but also to activate CO2 and CH4, accordingly enhancing syngas production, during cyclic CaLDRM. Importantly, the bifunctional material can succesfully drive CaLDRM cycles, converting over 40 % of CH4 and CO2, under 5 vol% CO2 feed concentration (as low as real flue gas) at 720 °C, which is a thermodynamically extremely unfavorable condition (equilibrium conversion below 3 %).

Toluene-Sensing Properties of Solid-Electrolyte Gas Sensors Using CeO2-Added Au Thin-Film As Sensing Electrodes

Introduction The exhaled breath of patients contains higher concentrations of specific gases than those of healthy people. For example, the patients suffering from lung cancer, diabetes and periodontitis release high concentrations of toluene, acetone and methylmercaptan, respectively. Among various kinds of gas sensors, solid-electrolyte gas sensors have shown enhanced sensing properties to volatile organic compounds (VOCs) by optimizing the microstructure as well as composition of the sensing electrode (SE) [1]. We have also reported that the addition of CeO2 to the Au SE of yttria-stabilized zirconia (YSZ)-based gas sensors increased the toluene response [2, 3]. In this study, thin-film CeO2-added Au SEs (thickness: 30‒100 nm) were fabricated by a spin-coating method, and their sensing properties to toluene were examined at 500°C. Experimental CeO2-added Au SEs were fabricated by a spin-coating method. The coating solution was prepared by the addition of Ce(NO3)3ˑ6H2O and polyvinyl alcohol into a 0.1 M HAuCl4 aqueous solution. The solution was dropped on the YSZ substrate, and it was spun at 3000 rpm for 30 s, followed by the heat treatment at 300°C. This process was repeated multiple times to increase the film thickness. Then, they were annealed at 700°C for 2 h in air. The obtained SEs were denoted as nCeO2/Au(x) SEs (n: an additive amount of CeO2, 8‒24 (wt%), x: the number of spin-coating cycle, 5–15). A Pt paste was screen-printed on the backside of the YSZ as the counter electrode (CE), and it was annealed at 700°C for 2 h in air. Response properties of the fabricated sensors (nCeO2/Au(x) sensors) to 50 ppm toluene in dry air were measured in a flow apparatus (gas-flow rate: 100 cm3 min−1) at 500°C. The SE was exposed to a sample gas, while the CE was always exposed to dry synthetic air during gas response measurements. The open circuit voltage between the two electrodes (E, mV) of the sensors as a sensing signal was measured with a digital electrometer, and the response (ΔE) was defined as the difference in E between in dry air and in toluene balanced with dry air. The microstructure of the sensors was observed by scanning electron microscopy (SEM; JEOL Ltd., JSM-7500F). Results and Discussion The thickness of the 8CeO2/Au(5) SE was very thin (ca. 30 nm), and the thickness increased with the number of spin-coating cycles. The SE thickness was not affected by the additive amounts of CeO2 in the examined number of spin-coating cycles (x). Therefore, the SE thickness was controlled from 30 to 100 nm only by changing the x value.Figure 1 shows response transients of the nCeO2/Au(x) sensors to 50 ppm toluene at 500°C in dry air. The E values of all the sensors negatively shifted upon exposure to toluene, but ΔE was largely affected by the SE thickness and the additive amount of CeO2. ΔE of the 8CeO2/Au(x) sensors largely decreased with an increase in the thickness of SEs. Generally, the VOC-sensing mechanism of solid-electrolyte gas sensors can be explained on the basis of the mixed potential theory [1‒3]. Based on the theory, the electrochemical oxidation of toluene and electrochemical reduction of oxygen simultaneously proceed at triple phase boundaries (TPBs) at the interface between SE and YSZ, when toluene diffuses in SE and reaches TPBs [2]. In addition, a certain amount of toluene is catalytically oxidized during the diffusion in SE. Therefore, the actual concentration of toluene at TPBs decreased with an increase in the SE thickness, which resulted in the largest toluene response of the 8CeO2/Au(5) sensor among the 8CeO2/Au(x) sensors. However, ΔE of the 24CeO2/Au(x) sensors increased with an increase in the thickness of SEs, and the 24CeO2/Au(15) sensor showed the largest ΔE (ca. 199 mV) among the sensors examined. The details of this phenomena will be discussed in the presentation.

Effects of micro/nano CeO2 on the microstructure and properties of WC-10Co cemented carbides

WC-10Co cemented carbide with micro/nano CeO2 additives was obtained through powder metallurgy technology. The effects of CeO2 grain size on the structure and performances were investigated by scanning electron microscope, X-ray diffraction, mechanical properties testers and friction testing machine. The results showed that the grain size of WC decreased after adding micro/nano CeO2, and the refining effect of nano CeO2 was better than that of micro CeO2. The properties of alloys such as Vickers hardness, TRS and fracture toughness increased with the increase of CeO2 additives, and then followed a decrease trend when the content of CeO2 exceeded 0.8%. Furthermore, the content of nano CeO2 greatly affected the cemented carbide and 0.4% of nano CeO2 revealed the strongest improvement on the structure and performances of WC-10Co cemented carbide.

Influence of CeO2 addition on forming quality and microstructure of TiCx-reinforced CrTi4-based laser cladding composite coating

TiCx-reinforced CrTi4-based composite coatings were successfully fabricated on a Ti6Al4V titanium alloy surface via laser cladding technology by using coaxial Ti6Al4V/NiCr-Cr3C2 mixed powders with different CeO2 contents (0, 1, 2, 3, and 4 wt%). The influence of CeO2 addition on the forming quality, phase composition, microstructure, and elemental distribution of the laser cladded coatings was investigated via penetrant flaw detection, optical microscopy, X-ray diffraction, scanning electron microscopy, energy spectrum analysis, electro-probe microanalysis, and transmission electron microscopy. The results showed that CeO2 addition can inhibit the formation of cracks and pores. The least number of cracks and pores were observed upon the addition of 2 wt% and 3 wt% of CeO2, respectively. The phases in the coatings consisted of vacant titanium carbide (TiCx) and β solid solution (CrTi4). The morphologies of TiCx in the transition, cladding, and bonding zones exhibited distinct granular, dendritic, and short needle-like differences, respectively. Notably, the addition of CeO2 did not affect the phase composition, but it significantly influenced the content of dendritic TiCx. The dendritic TiCx content was minimum (35%) for a CeO2 content of 3 wt%. The dendritic TiCx was mainly enriched by Ti and C, and the content of C in primary dendrites was higher than that in secondary dendrites. The Ce and O atoms from CeO2 decomposition were recrystallised as CeO2 and Ce2O3, and distributed in the interphase boundary between TiCx and CrTi4, within the TiCx and CrTi4 grains, and at their grain boundaries. The Al, V, and Cr elements were uniformly distributed in the matrix phase (CrTi4), while elements Ni and Cr appeared segregated.

Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050

Abstract In this paper, ceramic coatings were prepared on the surface of 7050 high strength aluminum alloy using a micro-arc oxidation process in a silicate electrolyte combined with the rare earth element cerium or graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and electrochemical measurements were used, respectively. It was shown that the micropore size of the composite coatings, which mainly consisted of α-Al2O3 and γ-Al2O3, decreases and the density improved with the simultaneous addition of 4 g · L-1 of CeO2 and 10 g · L-1 of graphene to the electrolyte. In addition, with the addition of CeO2 and graphene, the roughness was the lowest and the corrosion resistance was significantly improved.

Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050

Abstract In this paper, ceramic coatings were prepared on the surface of 7050 high strength aluminum alloy using a micro-arc oxidation process in a silicate electrolyte combined with the rare earth element cerium or graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and electrochemical measurements were used, respectively. It was shown that the micropore size of the composite coatings, which mainly consisted of α-Al2O3 and γ-Al2O3, decreases and the density improved with the simultaneous addition of 4 g · L-1 of CeO2 and 10 g · L-1 of graphene to the electrolyte. In addition, with the addition of CeO2 and graphene, the roughness was the lowest and the corrosion resistance was significantly improved.

Effect of CeO2 on the Structure of Silicate Glass Cured Body

In this paper, samples of xCeO2·(100-x) (SiO2·Al2O3·CaO) (x: 0∼15) glass solidified body was prepared by a high temperature melting method. The structural characteristics and thermal stability of CeO2 silicate glass-cured bodies were characterized by means of density porosity test, XRD, Raman, DSC and SEM. The results show that the addition of CeO2 does not change the basic structure of the glass, which is located in the pores of the silicate glass grid and plays a network modification role. When the added amount is less than 5% wt, homogeneous glass is easily formed. CeO2 is uniformly distributed in the glass body, and no enrichment occurs. When the added amount is more than 8% wt, CeO2 easily crystallizes during cooling.

Effects of CeO2 on the Si Precipitation Mechanism of SiCp/Al-Si Composite Prepared by Powder Metallurgy.

SiCp/Al-Si composites with different CeO2 contents were prepared by a powder metallurgy method. The effect of CeO2 content on the microstructure of the composites was studied. The mechanism of CeO2 on the precipitation of Si during sintering was analyzed by theoretical calculations. The results show that the appropriate amount of CeO2 can significantly refine the size of precipitated Si particles in the composite and increase the number of Si particles. With the increase of CeO2 content from 0 to 0.6 wt%, the number of Si particles precipitated in the composites increases gradually, and the average particle size of Si particles decreases gradually. When the CeO2 content is 0.6 wt%, the number of Si particles precipitated in the composites reaches the maximum, and the average particle size reaches the minimum. However, with the increase of CeO2 content from 0.6 wt% to 1.8 wt%, the number of Si particles precipitated in the composites began to decrease, and the average size of Si particles gradually increased. CeO2 can be used as heterogeneous nucleation substrate of precipitated Si, and the nucleation rate of precipitated Si on a CeO2 substrate is higher than that on an aluminum substrate. The proper addition of CeO2 can improve the nucleation efficiency of precipitated Si, thus increasing the amount and refining the size of precipitated Si.

Role of CeAl11O18 in reinforcing Al2O3/Ti composites by adding CeO2

AbstractThis work discusses the reinforcement effect of elongated CeAl11O18 phase on multifunctional Al2O3/Ti composites by adding CeO2 to inhibit interfacial reaction and strengthen interface for inducing optimized performances. For this purpose, Al2O3/Ti composite with different contents of CeO2 was fabricated and the microstructure, mechanical and electrical properties were studied. Results indicated that after CeO2 was added, elongated CeAl11O18 phase was formed within these composites. Owing to inhibited interfacial reaction between Al2O3 and Ti, Ti content was increased and compositions of composites were calculated using Rietveld method based on X‐ray diffraction patterns. Attributed to the strengthening and toughening effects of CeAl11O18 phase, 2 mol% CeO2 added composite showed the highest flexural strength and fracture toughness of 576 MPa and 5.15 MPa·m1/2, which increased by 21% and 20% compared to Al2O3/Ti composite without CeO2 addition. In this case, crack bridging by both Ti and CeAl11O18 particles was the major toughening mechanism and the additional fracture toughness caused by CeAl11O18 toughening effect reached a maximum. The role (crack bridging or particle pull‐out mechanism) of CeAl11O18 in toughening Al2O3/Ti composites depended on the aspect ratio of these elongated particles, which was directly related to CeO2 content. Because of the inhibition of interfacial reaction and the increase in Ti content, excellent electrical resistivity of composites after CeO2 addition was maintained in spite of the formation of insulated CeAl11O18 phase. All samples showed relatively low electrical resistivity of ~10−3 Ωcm.

Effect of CeO2 on the Microstructure and Properties of Plasma-Sprayed Al2O3-ZrO2 Ceramic Coatings

Al2O3-ZrO2 eutectic ceramic composite coatings with and without CeO2 addition were prepared by atmospheric plasma spraying. The microstructure and properties of the plasma-sprayed Al2O3-ZrO2-CeO2 coating were investigated. The results show that the Al2O3-ZrO2-CeO2 coating contained t-ZrO2, α-Al2O3 and γ-Al2O3 phases. Amorphous phase was found in the Al2O3-ZrO2 and Al2O3-ZrO2-CeO2 coatings, which was determined by the characteristics of the plasma spraying process and the eutectic composition of the composite powder. Compared the Al2O3-ZrO2-CeO2 coating with the Al2O3-ZrO2 coating, it was found that the Al2O3-ZrO2 coating with 4 wt.% CeO2 had lower porosity, more uniform and denser microstructure. The addition of 4 wt.% CeO2 was beneficial to improving the hardness, toughness, bond strength and wear resistance of the Al2O3-ZrO2 coating.